Process of recovery of volatile liquids.



G. CLAUDE.

PROCESS OF RECOVERY OF VOLATILE LIQUIDS.

APPLICATION FILED MALE, 1009.

Patented 0013. 8, 1912.

UNITED STATES PATENT OFFICE.

GEORGES CLAUDE, OF PARIS, FRANCE, ASSIGNOR TO'LAIR LIQUIDE, SOCIETE ANONYME POUR LE'IUDE ET LEXPLOITATION DES PROCEDES GEORGES CLAUDE, OF PARIS,

FRANCE.

PROCESS OF RECOVERY Application filed March 5,

Specification of Letters Patent.

OF VOLATILE LIQUIDS.

Patented oct. s, 1912.

1908. Serial No. 481,528.

To all whom 'it may concern:

Be it known that I, Gnonons CLAUpn, a citizen of the Republic of France, resldmg in Paris, France, have invented certain new and useful Improvements in Processes of Recovery of Volatile Liquids Contained in the Form of Dilute Vapors in Air, of which the'following is a s ecification.

In many industries enormous quantities of air or gas are charged with small quantities of the vapors of volatile liquids. Suc h for example are the industry of making artificial silk. by the collodion process, and the industry of making smokeless powder, where the diluted vapors which occur in large volumes of air are composed of alcohol, ether, and atmospheric humidity. Among the rocesses which have already been proposed or recovering these vapors, that which seems the'simplest is the physical process consisting in compressing the air or the gas which contains the vapors to be extracted, in cooling such air and causing it to pass in in direct cont-act with gas previously expanded, and in ex anding it'finally, approximately at atmospheric pressure for example. The cooling obtained in this process should be pushed to a sufiioiently low temperature to reduce to a negligible point the tension of before the air arrives at the expansion apparatus. But this process presents a difliculty in practice by reason of the low tem-. peratures-which are necessary for condensation, the condensed products tending to freeze or congeal in whole or in art. This freezing causes obstructions in t e apparatus. It is then necessary to stop the use of, this apparatus, to substitute another apparatus t erefor, and to re-heat the first apparatus before again utting it to use. This requires difiicult and expensive manipulations.

The purpose of the present invention is toremedy these difiiculties. It takes adva'n tage of the relative andgradual difiiculty of freezing mixtures .ofwater and alcohol, and then of alcohol and ether (in those cases in which there are water va or, alcohol and ether vapors contained in t e air to be treatcape all chance of freezing by reason of a special method of circulation. v

The accompanying drawings illustrate diagrammatically suitable apparatus" for carrying out the processrFi'gures 1 and 2 being respectively two different types of apparatus.

The air or gas containing, say, water vapor from the atmosphere and small quantities of alcohol and ether vapors which it is desired to recover, after having been filtered if necessary, is compressed to a pressure of several atmospheres either in a piston compressor or in a suitable rotary ap aratus; If coolin water is sprayed into t e compressor, t is must naturally be moderated in order to avoid a loss of the products by absorption by the water; the water can be used several times after cooling, and can ultimately be treated for alcohol. The air is cooled during and after the com ression as completely as the temperature 0 the water allows; not only to increase the yield of the compression but also to condense all that part of the water va or (with more or less uantities of alcoho which exceeds the limit of saturation at the temperature of coolin This apparatus is, for example, formed b in which cold water circulates. It is important to remove as much water as possible at this stage, for its heat of condensation is in this manner given up to the cooling water instead of neutralizing a part of the costly cold produced at low temperature in the expans on, as hereinafter e lained. 'If this first condensation should e, insufficient, if for example the cooling water at hand were may be completed by that of refrigerating liquid borrowed from an auxillary refrigeratlng machine. These first litkue'fied portions, collected in the collector placed at y a coil 0 placed in a receptacle 0! not cold enough, its act1on on the air treated the bottom of the coil and having a draw-ofi' of its, vapors arrives atthe apparatus which the remainder of its vapors is re-- moved in a. 1i uid state.- This apparatus may be forms by two lipuefying'interchangers or condensers A an type and an expansion machine M of suit- B of a suitable able type, cylinder-with piston or, turbine. The whole of this is protected by a suitable insulating casing to prevent the apparatus from bein heated by the atmosphere. The compressed air is passed into the nest of tubes 11, becoming gradually cooled there owing to the expanded air circulating around the tubes and in the opposite direc-'-' tion. This brings about condensations which will be analyzed presently; then the air arrives at the machine M, expands there with production of externalwork, and the expanded air is sent back into the casing of B and then of A in the opposite direct-ion to the incoming compressed air. The tubes a and b of these two interchangers A'and B are arranged in such a way that the products which are condensed there are brought in a liquid state into the collectors J and K whence they can be drawn oif into the open, automatically or not by taps R B In the tubes- 0 of the vessel A the cooling of the compressed air is regulated in the manner hereinafter described so as to liquefy the remaining water and part of the alcohol but to prevent the alcoholic liquid that is formed from being frozen at the coldest part of the exchanger, which is evidently the lowermost part. The liquid produced in this second condensation is collected outside, after having been deprived of its coldness or not, as desired.

Supposing that the temperature at the .cold end of A is very, much below 0, for example, --30, the tension of the water vapor has become very small in spite of the presence of the alcohol; the compressed air which passes from A to enter B will therefore contain only ether and a little alcohol, with a small quantity of water, so small as to be incapable of appreciably raising by its presence, the temperature of solidification (from A 110 to 120) of mixtures of al-.

cohol and .ether. It becomes therefore pos- Y sible to subject the fluid in its passage through E to progressively decreasing temperatures down to the above mentioned exceedingly low limit without fear of any solid matter being formed and thus to effect a very complete condensationof the vapors of alcohol and ether only in a liquid state.

It is therefore practically pure air which comes to be expanded in M. A quantity of liquid or solid matter so exceedingly small as to be negligible may perhaps form at the moment of expansion in the apparatus M owlng to the sudden fall in temperature caused'by the expansion, but this small quantity of .matter may be separated from the exhaust air, by a filter, for example. The; cold expanded air circulates throu h the temperature exchangers A and B arouhd the tubes a and b? The/important condition attached to the successful carryingout of this process is to aoeosee so regulate the temperatures in the temperature exchangers as to prevent solid matter "from being formed at any part, and particularly in the exchanger The temperatures at the various parts of the exchangers must be carefully watched, the observations being made by means of ordinary thermom- 'eters or thermo-electric couples. If the temperature falls excessively in the exchanger A, some of the cold expanded air issuing from the exchanger B should be prevented from entering the said exchanger A and be led away therefrom by manipulating the valve V in the pipe B. Similarlythe valve V in the passage on should'be mani ulated if the temperature in the coldest lower) end of exchanger B becomes excessively low. I The liquids collected in the vessels 1, J and K can be treated in anyappropriate manner for the separation of their constituents, but if they are at temperatures much below their boiling points, their excessive coldness may, if desired, be taken advantage of for; cooling purposes in any desired manner before they are subjected to any separating treatment.

The most natural method of utilizing the excessive coldness of the liquefied vapors is to modify the apparatus so as to cause the compressed air to circulate in the manner shown in Fig. 2. In this modified form of apparatus it will be seen that the liquids produced by the condensation of the vapors of gravity, travel in the tubes of the exchangers in the opposite direction to and in direct contact with the airto be expanded, the result being that the said liquids do not collect at the cold ends of the exchangers but at their warm ends. Moreover, in this manner some of the advantages that exist in the separation of the constituents of gases by partial liquefaction of the gases and the backward return of theliquefied portions in the opposite direction to and in contact with further quantities of the gases to be separated, as set forth in the prior U. S. Patent place of the arrangeme'nt shown in Fig. 1

changers areso large in sectional area, and the velocities of the air to be treated are so low, "that the liquids formed in and flowing down the tubes'will be prevented from being carried along by the ascending air.

As the air charged with vapors to be recovered, water, alcohol and ether in the contained in the air will, under the influence No. 924,428, will also be obtained; it may .120 the same;.-ii ;f. can however be employed in only when the tubes employed in 'fthe ex- 30 are of successively lower reezing point, as

' tubes a, they ineet with temperatures which .say the water vapor.

are gradually lower. They finally reach a temperature corresponding to the saturation of the most easily condensable vapor, At this point the water vapor commences to condense. But

' it carries with it a certain quantity of alit passes through cohol, so that the liquid can not congeal except at a temperature much below 0. Now since the liquid is formed without co elation, it can always run downward wit out risk of being congealed, since in its descent a, region of gradually increasing warmt As to the gas remainin after the condensation of water and alcoho has'commenced, this gas contains less of the water vapor." It continues to rise into the regions of lower and lower temperatures. At a farther point, in the tubes 1) for example, the temperature of saturation occurs for this mixture, and a liquid is formed containing alcohol of a very low freezin point, and as this runs down the tubes 1t 'encounters higher temperatures and thus entirely escapes any danger of freezing. Therefore as the process is continued, the liquids formed are always rundown into higher temperatures, so that they cannot freeze, and the successivel formed liquids water, alcohol, and ether; the latter being capable of standing a, temperature of -11 without freezing. The liquid recovered in the vessels J and K is in the neighborhood,

of ordinary temperatures, after having given up a quantit. of its cold to the ascending gas during t e descent of the liquid.

Obviously the present process is appli;

cable to the treatment of air containing small quantities of volatile substances besides the air involved in the manufacture of silk or smokeless Claims: 1. A process of recovering by liquefaction, volatile liquids'contained in the condition of dilute vapors in large volumes of powder.

air or gas, which consists in compressing 1 iquefg the v0 atile portions, so that the liqormed run toward spaces which are I using it for cooling successive quantities of the air or gas containing the volatile vapors to be recovered.

2. A process of recovering by liquefaction, volatile liquids contained in the form of dilute vapors in large volumes of air or gas, which consists in compressing the air or .gas containing the vapors to be recovered, submittin it to a preliminary cooling by means of 00 d water, then submitting it to temperatures progressively lower in order to liquefy progressively the volatile matters by circulating it met contact with air or gas previously expanded and cooled, efi'ectin the circulation 1n such a way that the liquidsformed by the volatile matters run in such a direction as to be progressively heated, and finally ex andmg the air or gas thus freed from volatile matters and circulating it methodically so as to progressively cool further quantities of air or gas containing the volatlle vapors to be recovered.

3. The process of recovering by liquefaction alcohol and ether contained in the form of dilute vapors at ordinary temperatures in large volumes of atmospheric air, WhlCl'l consists in compressing the atmospheric air con-. taining the vapors of alcohol and ether, coolodically in indirect ous'ly expanded in such a way as to llquefy progressively substantially all the alcohol and causing it to run in such a direction as to be reheated to approximately ordinary temperature, ca ing other with the air freed from alcoho condensing this ether to a liquid, allowing the air thus purified to expand, and circulating it methodically so as to progressively cool further quantities of air containing alcohol and ether. In witness whereof, I have .hereunto si ed my name in the presence of two su b scribing witnesses.

GEORGES CLAUDE. Witnesses: v

I r ELLWOOD AUs'rm WnLnnN,

GABRIEL Bmmann. 

